For many computer users the conventional mouse is an invitation to experience Repetitive Strain Injury Syndrome, or RSI. RSI is a well documented and recognized medical condition, and RSI from using a conventional computer mouse is understood to affect a significant percentage of the workforce that uses computers. See, for example the book entitled Repetitive Strain Injury A Computer User""s Guide by Emil Paccarelli, M.D., and Deborah Quilter (ISBN 0-471-59533-0, John Wiley and Sons Inc., 1994) On page 167 they lay the blame for many serious cases of RSI on the use of a computer mouse. We shall term such injuries (and they are nothing less than genuine injuries) xe2x80x9cmouse RSIxe2x80x9d.
In simple terms, the primary cause of mouse RSI is the unnatural inwardly rolled position of the hand (palm parallel to the desk top) required by the shape of a conventional mouse and the location of the buttons, or finger actuated controls, thereon. A more neutral position is one where the palm of the hand and wrist are 45xc2x0 to 90xc2x0 less twisted. Continued unnatural twisting causes the tendons to assume contorted paths and subsequently chafe in their sheaths. The conventional xe2x80x9cbar of soapxe2x80x9d mouse, with its side-by-side horizontally aligned keys, forces an extreme unnatural position of the hand.
This problem has not gone unrecognized by mouse designers and manufacturers. There are a number of mouse products that have been brought to market that have attempted to alleviate mouse RSI. There have been pistol grip designs. These do not require an unnatural hand position, but are notorious for lack of ease in fine positioning of the screen pointer, owing to the fact that both wrist and arm motions are needed, rather than allowing the heel of the palm to anchor fine motions of the fingers. Track balls tend to require the same or nearly the same amount of unnatural twisting as does a conventional mouse. A stylus for a tablet is generally easily and naturally held, but is inefficient to lay down and pick up again. Also, buttons or keys located on a stylus are usually not convenient to actuate.
Accordingly, it would be highly desirable if there were a computer pointing device that matches the conventional computer mouse in functionality (ease of fine positioning, free standing, etc.), but that is gripped in a more natural and in a less or non-damaging way, so as to reduce or eliminate any mouse RSI associated with its use.
An ergonomic mouse that alleviates mouse RSI is obtained by gripping the mouse with a pinching action between the thumb and opposing fingers while the mouse is in the U-shaped opening formed in the hand when in a neutral and unflexed condition with the little finger and the heel of the palm opposite the thumb resting upon a work surface. The mouse has two gripping surfaces; one receives the thumb and the other the opposing fingers. Indentations in the gripping surfaces help locate the finger tips. Mouse buttons are located in the indentations. The gripping surfaces are inclined toward each other, so that the pinching action to actuate the mouse buttons produces a slight downward force toward a base surface that rests upon and slides over the work surface. This acts to provide stability as the mouse buttons are pressed. The third and the fourth (little) finger may be allowed to drag on the work surface to provide tactile feedback and assist in fine positioning. Preferably, the mouse utilizes an optical motion sensing technique instead of the conventional rubber coated steel ball.